Wear plate for floating roof tank



Aug. 5, 1958 c. E. STOYER WEAR PLATE FOR FLOATING ROOF TANK Filed Sept. 14, 1956 W I z 02%; 0 e7:

United States Patent WEAR PLATE FOR FLOATING ROOF TANK Clifford E. Stoyer, Greenville, Pa., assignor to Chicago Bridge & Iron Company, a corporation of Illinois Application September 14, 1956, Serial No. 609,990

7 Claims. (Cl. 220-26) This invention relates to a wear plate for use in conjunction with a floating roof in a liquid storage tank.

Liquid storage tanks employing a floating roof as the top closure for the liquid stored therein are being widely adopted as the most efficient method of storing volatile liquids, such as petroleum products. Such tanks have a floating roof which seals the contents of the tank from the atmosphere. My invention contemplates a wear plate for use in floating roof tanks which is in intimate scraping contact with the inside surface of the side walls of the tank.

My invention is particularly useful in tanks storing waxy or gummy petroleum products where there is a tendency for wax and/ or gum to deposit along the inner surfaces of the tank so as to prevent the proper functioning and sealing of the floating roof. For example, crude oil produced in the Middle East contains large amounts of waxy substances, and where such crudes are stored in floating roof tanks of conventional design, the shoes which slidably contact the interior surface of the side wall of the tank may stick to the inside surface of the tank because of the accumulation of waxy deposits; these deposits inhibit or prevent the roof from properly rising and falling with changes in the liquid level. The surface irregularities formed by such deposits on the interior surface of the side wall of the tank also tend to destroy the effectiveness of the seal.

These difliculties may be obviated by the use of my Wear plates, each of which has a sharp scraping edge which bears against the inside surface of the side wall of the tank so that the wear plate may scrape accumulated Waxy and/or gummy substancesofi the side wall 11 as the roof moves up and down inside the tank. This scraping action causes the deposited materials to drop to the bottom Where they are not troublesome and can be readily removed.

The invention will be described in the embodiment disclosed in the accompanying drawings which illustrate the use of my wear plates in conjunction with a hangerpusher type sealing mechanism such as a weighted pantagraph as shown in Figure 1. However, my wear plates may be used in combination with other sealing mechanisms.

In the accompanying drawings:

Figure 1 is a vertical section through a liquid storage tank showing portions of the side wall, the floating roof, my wear plate, and the liquid stored in the tank; and

Figure 2 is a perspective view of one of my wear plates.

Referring now to Figure 1, 10 indicates a liquid storage tank having a side wall 11 and a floating roof 12 floating upon the surface of the liquid 13 contained in the tank. The floating roof 12 has a top 14, a side 15, terminating in an upper rim 15a, and a bottom 16. An annular seal 17 of flexible material is secured to the annular rim 15a of the roof and to the upper ends and shoes 19, which generally conform to the contour of the side wall 11, by any suitable fastening means 21 and 22 6 2,846,110 Patented Aug. 5, 1958 (such as nuts and bolts), respectively, so as to seal the space 18 between the side wall 11 of the tank and the floating roof 12. Wear plates 23 are secured to the plurality of shoes 19 in a manner described later. The shoes are suspended and hold the wear plates 23 in surface-to-surface contact with the side wall 11 by the hanger-pusher mechanism 25, such as a weighted pantagraph. The roof 12 floats on the liquid 13 and rises and falls as the level of the liquid is raised or lowered, during which movement the wear plates 23 slidably contact the side wall of the tank.

Each wear plate, as illustrated in Figure 2, may be constructed of thin flexible metal material such as 16 gauge galvanized steel and has at its lower end a V- shaped rib 26 projecting inwardly and having a substantially horizontal lower leg 27 projecting outwardly, that is, toward the tank wall 11 and formed with a sharp scraping edge 28 at its free end; the edge 28 extends outwardly just beyond the vertical plane of the main elongated body of the Wear plate and has an upper beveled surface. The flexible metal of the wear plate 23 and the spring-like rib provide flexibility to the wear plate so that the sharp scraping edge 28 is urged into intimate metal-to-metal scraping contact with the side wall 11 of the tank. However, the force urging the edge 28 into contact with the side wall 11 is not sufficient to prevent the wear plates from sliding up or down the side wall as the roof 12 moves with the changing level of fluid in the tank.

Accumulation of waxy and/or gummy deposits 30 are removed from the side walls as the sharp scraping edges 28 of the wear plates move downwardly, and the freed deposits fall to the bottom of the tank. These deposits may be removed from the tank through access openings when the tank is drained.

The upper portion 31 of the wear plate is flared inwardly away from the side of the tank. This flared portion serves as a ledge to retain dried or hardened wax or gummy material which has escaped from the action of the scrapingedge 28 and which may flake off the side wall 11.

As shown in the drawings, the wear plates 23 are attached to the shoes 19 so that they may be readily removed, repaired, or replaced without removing the tank from service.

The. wear plates are attached to the shoes by the fastening means 22, which are accessible from above the top 14 of the roof 12. That is the same fastening means which secures the flexible seal 17 to the shoes 19 pass through holes 32 in the wear plates and support the latter. Preferably the bolt holes 32 are countersunk into the wear plate so that bolt heads will not extend beyond the main body of each of the wear plates which are positioned around the interior surface of the side wall in laterally abutting or contiguous relationship to each other. While a hanger-pusher type of mechanism of the type shown in the Moyer et a1. Patent Number 2,587,508 is shown, it will be understood that other equivalent means may be employed instead.

My wear plates may be placed in existing floating roof tanks of conventional design, thus enabling the economical adaptation of existing storage tanks. In addition, if desired, the Wear plates may be attached directly to a hanger-pusher mechanism; the Wear plates may be thus used as shoes and, at the same time, serve as scraping means.

When the wear plates are to be used on tanks of relatively large diameter, as for example feet, the amount of curvature in the wear plate to accommodate to the curvature of the tank shell becomes insignificant and may, for all practical purposes, be ignored. In this situation wear plates having flat surfaces instead of cylindrical sureflicient operation, be curved to the actual curvature of the tank in which the wear plate is to operate.

The term substantially flat is hereinafter intended to refer to wear plates having a main body portion that is flat or very slightly curved.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. A metal wear plate for use in a floating roof storage tank comprising a main body portion having a cylindrical segmental contour conforming. to the curvature of the side wall of a storage tank so as to have an outer face capable of sliding in face-to-face contact with the interior surface of said side wall, said body portion having an outwardly projecting convex curvature, the bottom portion of said body portion having a laterally extending flexible rib that projects inwardly from said main body, the lower free leg of said rib being positioned so as to project outwardly beyond the outer face of said main portion, said lower free leg having a sharp scraping edge at its free end, said scraping edge being capable of providing intimate metal-to-metal scraping contact with said interior surface of said side wallwhile the outer face of said main portion is in face-to-face contact with said interior surface of the side wall.

2. The wear plate of claim 1 wherein said lower free legzof said rib projects outwardly in a substantially horizontal plane.

3. The wear plate of claim 1 wherein the upper portion of said lower free leg of said'rib has a beveled surface that terminates in said sharp scrapinged'ge.

4. The wear plate of claim 1 wherein the'upper portion of said body portion is flaredinwardly so as to retain foreign substances which are freed from the interior surface of the side wall of the storage tank.

5. In a floating roof storage tank having a floating roof with annular flexible sealing means secured to pcripheral edges of the roof and a pusher-hanger means for maintaining the sealing means in sealing relation with the interior cylindrical surface of the side Wallof'the tank, the improvement comprising a plurality of wear plates connected to said pusher-hanger means and urged into sliding face-to-face contact with the interior surface of said side wall by said pusher-hanger means, each of'said wear plates comprising-a main body portion having a cylindrical segmental contour conforming to the curvature of the side wall of a storage tank so as to have an outer face capable of sliding in face-to-face contact with the interior surface of said side wall, the bottom portion of said body portion having an inwardly extending flexible rib, the lower free leg of said rib projecting outwardly beyond the outer face of said main portion, said lower free leg having a sharp scraping edge at its free end, said scraping edge being capable of providing intimate metalto-metal scraping contact with said interior surface of said side wall while the outer face of said main portion is in face-to-face contact with said interior surface of the side wall.

6. In a floating roof storage tank, the improvement of claim 5, wherein the upper portion of said body portion is flared inwardly was to retain foreign substances which are free from the interior surface of the side wall of a storage tank.

7. In a floating roof storage tank having a floating roof with annular sealing means between. the roof and side wall of the tank comprising, a flexible seal and shoe the latter being secured to peripheral edges of the roof urged toward the interior cylindricalsurface of the side wall of tank by pusher-hanger means, the improvement compris-v ing a plurality of wear plates between said shoes and said tank and urged'into sliding face-to-face contactwith the interior surface of said side wall by said pusher-hanger means, each of said, wear plates comprising a main body portion having a cylindrical segmental contour conforming to the curvature of the side wall-of a storage tank so. as to have an outer face capable ofsliding in face-to-face contact with the interior surface of said. side wall, the bottom portion of' said. body portion having a rib that projects inwardly from said main body, the lower. free leg of said rib being positioned so as to project outwardly beyond the outer face of said main portion, said lower free leg having a sharp scraping edgeat its free. end, said scraping edge being capable of providing inti-. mate metal-to-metal' scraping contact with-said interior surface of said side wall while the outer face. of said main portion is in face-to-face contact with said interior surface of the side wall.

References Cited in the tile of this patent UNITED STATES- PATENTS 1,900,904 Berger Mar. 14, 1933 2,098,408 Watson Nov. 9, 1937 2,685,503 Knecht Aug. 3, 1954 FOREIGN PATENTS- 165,572 Australia -.Oct. 12, 1955 Patent No, 2,846,110 August 5, 1958 Clifford E, Stoyer It is hereby certified that error appears in the printed epeeifieetion of the above numbered patent requiring correction and mm the said. Letters Patent should read as corrected below.

Column 4, line 15, for "free" read freed w Signed and sealed this 18th day of November 1958o (SEAL) Attest:

KARL ROBERT c. ATSON Attesting Oflicer Commissioner of Patents 

